Integrated circuit fabrication begins with a thin slice of single crystal semiconductor, usually silicon, and employs a combination of physical and chemical processes to create the integrated circuit structure. The fabrication process is very sensitive to particulate contamination and airborne particulates must be minimized during the fabrication sequence, as even very small particles on the wafer surface may cause device defects. A reduced particle fabrication ambience is normally achieved by the use of vertical laminar-flow (VLF) clean rooms. Lint-free garments are normally worn by persons working within those clean rooms to minimize operator-borne particles.
Tests have shown, however, that clean rooms can only reduce airborne particulate levels to approximately 10-20 particles per cubic foot in areas where people are working, though clean levels of less than one particle per cubic foot can be achieved in areas aerodynamically isolated from people. Thus, where particle contamination densities of less than one particle per cubic foot are required, the semiconductor slices cannot be exposed to VLF air in a clean room occupied by people. A need arises therefore for a container or carrier for storing and transporting semiconductor slice cassettes within the clean room that shields the slices from this VLF air. Various snap-top plastic boxes are currently in use for storage and transportation of slice cassettes within the clean room environment. Those boxes do not, however, have features to reduce particulate contamination and thus do not adequately protect the slices from the people-occupied environment.
The present invention improves upon the prior art by providing a carrier for semiconductor slice cassettes that shields the slices from people-occupied environments. The carrier is designed for storage and transportation of the semiconductor slices cassette within the clean room and maintains a clean environment around the slices.